Photographic screen



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M. RUHLANU PHOTOGRAPHIG SCREEN Original Files@ March 22 1915 /n/ van' To@ rowwry lll tid

Patented hug.. 7, ld;

1"nesren'on re nuotare @runnin GERMANY.

application nei nana aa' rois, serai ne. rasate.

Renewed lune tt, tutti.

(@lilllltfllil UNDER THE EROVISIQNS 0F THE ACT @F MARCH 3, i921, il STAT. L., 1313.)

.To all whom t may concern.'

Be it known that l, MAX RUHLA'ND, a sub- 'ect of the German Emperor, residing at o. 18/1 Frundsbergstrasse, Munich, Germany, have invented certain new and useful improvements in Photographic Screens' (for which ll have tiled an application in Germany March 22, 1912, B 66812 Vil/57d), of which the following is a specification. 'lhis invention relates to screens for photographic reproducing purposes and particularly to screens used in the reproduction of colors, paper securities or whenever one or more screens are used and especially where two or more screens are used, as inthe photolithographic reproduction oi colors.

Heretoiore screens oi more or less regularity of pattern have been used for this purpose, requiring that the screens must be exactly placed relative to each other in order to avoid striped, spotted or patterned appearance in the finished picture. Various unsatisfactory methods have been devised to avoid this defect.

rlhe principal object of the present invention is to provide a satisfactory screen in -which exact relative placement oi the screens is not required in order to avoid striped, spotted or patterned appearance in the finished picture though the screen need not be limited to thls particular use.v p

To this end ll have provided a screen provided with irregular polygons of substantially the same superficial area but not having any exact regular arrangement relative to-each other except that the boundaries between the polygons have the same width. Either the boundaries or the polygons may be light or darli.

The accompanying drawing shows two ot many possible embodiments of the invention.

Fig. 1 is a tace view of one form oi the invention, and

lFig. 2 is aI face view of another form.

ln one form the polygons 5 are lighter than the boundaries 6 and in the other the pplygons 5 are heavier than the boundaries 6 The arrangement of the screens can be easily seen in the drawing. lt will be noted that each polygon has a substantially ditferent shape from all of the adjacent polygens, though the areas thereof are the same or approximately so. 'llhe boundaries have substantially the same widthv throughout, but that portion of the boundary between each adjacent pair either out ofalinement with the adjacent portion oi that boundary, or out of parallelism with the neighboring boundaries, practically alwas both.

This new screen is suitab e for use in all reproducing processes in which a screen can be 1Iproduced..

claim as my invention 1. A halftone screen comprising a plurality of polygons, all irregular, and each having approximately the same su erficial area, and all being irregularly place. on the surface of a plate in such a manner that the boundaries between the polygons have the same width.

2. A screen for photographic reproducing processes havin screen aertures constituted by irregu arly distri uted irregular polygons of equal areas, and lines of equal width serving as boundaries or sides of said polygons 3. A screen comprising a plurality oil irregular polygons.

4. A screen comprising a plurality of irregular polygons having substantially the same area.

5. A photographic screen comprising a plurality oi irregular polygons having straight edges and e ual areas, each polygon having a sha e ierent from the adjacent polygons, t e boundaries between the polygons aving equal width throughout.

6. A. photographic screen comprising a plurality ot irregular polygons having stra-ight edges and e ual areas, each polygon having a shape ifferent from the adjacent polygons, the boundaries between the polygons having equal width throughout, the ratio of polygon to boundary being equal throughout all parts of the screen.

7. A. photographic screen comprising a plurality of 'irregular polygons having straight edges and equal areas, each polygon having a shape di'erent from the aol- ]acent polygons, the boundaries between the pol gens having equal width throughout, said7 boundaries extended across each other at approximately every conceivable angle.

8. A photographic screen comprising a plurality of irregular polygons ot equal lltlll Mld area, each having a -different shape., to any.

of the adjacent polygng, a

gona having stralght sides joining in angles, 5 some 0f the an les beingreex', Some obtuse,

some right ang esv and some acute angles.

10. A photograEhic screen comprisin Eglygons divided y boundarylines, eac

undary line-having aconstant width and l0 being out of parallellsm with adjacent lines.

11. A photographicl screen comprisin Eolygons divided by boundary lines, eac

oundary line having a constant width and being out of parallelism with adjacent lines, A

diferent parte of each. line being out of 1I y j parallelism with each. other. 9. A photographic screen coxnprising polyu '12. A .photographic screen provided with boundaries of constant width some part of 'every line'be'ing Iout of parallelism with someother art of itself and some part of i0 every other. ine.

In testimon whereof I aix my signature in presence o two witn.

MAX RUHLAND. Witnesses A. O. W. Comi, JOHANNA STERN. 

